San Francisco will require all city employees to be vaccinated.

The city of San Francisco said on Wednesday that it would require all 35,000 of its employees to be vaccinated against Covid-19 or risk losing their jobs, making it one of the largest U.S. municipalities to impose a vaccine mandate for public workers.

The requirement will take effect once a Covid vaccine receives full authorization from the Food and Drug Administration. The vaccines are currently being used in the United States under emergency authorizations.

City officials said that the requirement would promote safety in municipal workplaces and among the general public, given that police officers, firefighters, building inspectors and other city workers come into regular contact with members of the community.

“With those two things in mind — the safety of our employees and the safety of the public we serve — we made this decision,” said Carol Isen, San Francisco’s director of human resources. “We believe this step is a simple one to take. It’s safe, it’s very effective, and it’s going to guarantee the safety of all.”

San Francisco has one of the highest vaccination rates of any major U.S. city, with 80 percent of residents 12 and older having received at least one dose and 70 percent fully vaccinated, Mayor London Breed said this month. Ms. Isen said that informal surveys of city workers — many of whom live in other municipalities where vaccination rates are lower — suggested that at least 60 percent were fully vaccinated.

Under the new policy, starting on Monday, city employees will be required to show proof of their vaccination status within 30 days. City officials said that they would redouble efforts to get shots to those who haven’t had them, while allowing workers to request exemptions on medical or religious grounds.

Both Pfizer and Moderna, the makers of the two most widely used Covid shots the United States, have applied for full F.D.A. approval for their vaccines, but it is unclear when regulators will make a decision.

Elsewhere in the United States, vaccine mandates have been met with opposition. This week, more than 150 staff members at a Houston-area hospital were fired or resigned for not following a policy that requires employees to be vaccinated against Covid-19.

San Francisco officials said that employees who did not meet the vaccine requirement could lose their jobs, but added that firings would be a last resort. A recent outbreak of the Delta variant among unvaccinated residents in nearby Marin County — where more than 80 percent of people are fully inoculated — shows the need for everyone to receive the shots, officials said.

“We see that Delta did make its way through a cluster of unvaccinated people, and so we just wanted to make this move quickly,” Ms. Isen said. “We hope our employees respond to this in the spirit in which it’s offered — not as a punishment, but as a safety measure.”